Authorities in China and beyond stepped up efforts to control an outbreak of a new flu-like coronavirus on Wednesday as the death toll rose to nine with 440 confirmed cases, while suspicion grew that the virus crossed to humans from animals.
China discouraged public gatherings in Hubei province, where the virus emerged last month, and tightened containment measures in hospitals, while the World Health Organization (WHO) was due to hold an emergency meeting to determine whether the outbreak constituted a global health emergency.
The virus has spread from the central Chinese city of Wuhan, in Hubei, to Beijing, Shanghai, Macau, Hong Kong, and beyond to the United States, Thailand, South Korea, Japan and Taiwan.
The Chinese government has provided updates on the number of cases in a bid to head off panic, as hundreds of millions of people prepare to travel at home and abroad for Lunar New Year celebrations starting this week.
"The rise in the mobility of the public has objectively increased the risk of the epidemic spreading and the difficulty of prevention and control," National Health Commission vice-minister Li Bin told reporters.
There was evidence that the virus was being spread through "respiratory transmission", Li said. And, the director-general of China's Center for Disease Control and Prevention, Gao Fu, said virus was adapting and mutating, underscoring the challenges for health authorities.
Some 2,197 people who came into contact with infected people were being kept in isolation, while 765 have been released from observation.
"There has been a big change in the number of cases, which is related to our deepening understanding of the disease, improving diagnostic methods and optimising the distribution of diagnostic kits," Li said.
Symptoms of the virus, which can cause pneumonia, include fever, coughing and difficulty breathing.
There is no vaccine for the virus, which can be passed from person to person. Fifteen medical personnel are among those infected in China.
Fears of a pandemic similar to an outbreak of Severe Acute Respiratory Syndrome (SARS) that started in China and killed nearly 800 people in 2002-2003 have roiled global markets, with aviation and luxury goods stocks hit particularly hard and the Chinese yuan tumbling.
Companies across China, from Foxconn to Huawei Technologies and HSBC Holdings, were warning staff to avoid Wuhan and handing out masks.
Terry Gou, the billionaire founder of Apple supplier Foxconn, said he was advising company employees not to visit China over the holiday.
WHO spokesman Tarik Jasarevic said new cases of the coronavirus would appear as China stepped up monitoring.
Li said there was no evidence of "super-spreaders" capable of disseminating the virus more widely, as happened during the SARS outbreak.
Health authorities are still trying to determine the origin of the virus, which officials say came from a market in Wuhan where wildlife was traded illegally. SARS was believed to have crossed to humans from civet cats sold for food in China.
The WHO says an animal source appears most likely to be the primary source of this outbreak.
Taiwan on Tuesday confirmed its first case of the coronavirus, a woman returning from Wuhan.
The island's president, Tsai Ing-wen, called on China to share "correct" information about the virus and for the WHO not to exclude Taiwan from collaboration on the outbreak for political reasons.
Taiwan is not a member of the WHO due to the objection of China, which considers the island a Chinese province with no right to participate in international organisations unless it accepts it is part of China.
Like Australia, Taiwan warned citizens to avoid Wuhan, while banning tour groups from the city.
Airports around the world have stepped up screening of travellers from China.
The Chinese-ruled gambling hub of Macau confirmed its first case of pneumonia linked to the coronavirus and tightened body-temperature screening measures in casinos and around the city.
A first case of the virus emerged in nearby Hong Kong on Wednesday, media reported. The patient arrived in Hong Kong via high-speed railway from the mainland and had been quarantined, media said.
The city's commerce secretary, Edward Yau, said earlier authorities were on high alert.
"The whole world is watching," Yau told Reuters at the annual meeting of the World Economic Forum in Davos.
Several foreign tour operators said North Korea banned foreign tourists from Wednesday due to the virus, losing one of its main sources of foreign currency.
Some qualifying boxing matches for the 2020 Olympics set to take place in Wuhan in February had been cancelled, Japan's Kyodo news agency said.
Hong Kong's Cathay Pacific Airways Ltd said it would allow flight attendants to wear surgical masks while on mainland China flights.
Cathay said rebooking, rerouting and refund charges would be waived for all tickets to or from Wuhan through Feb. 15. China's aviation regulator has told mainland carriers to refund or change flights to Wuhan without charge.